1) You should handle the GroupBar.NavigationPaneDropDownClick event and appending new items to the default drop-down menu.

2) We have logged it as a feature request and notified our development team. We will implement this feature in our forthcoming new version releases or service pack releases. We usually have a timeframe of at least three months between releases. The feature implementation would also greatly depend on the factors like product design, code compatibility and complexity. We will get back to you once the feature is implemented.

3) This can be achieved by the following code snippet.

this.groupBar1.InplaceRenameItem(index);// Where index represents the index of the GroupBarItem